So today we are going to be talking about complications in in general anaesthesia. What we are going to cover in this session is, is going to be some examples of, of, of complications. We are going to be talking about some cardiovascular complications which probably are some of the, the most common ones that we tend to see, respiratory complications as well.
I, I put this, a group, just a miscellaneous group like, calling them orders, some of them can be quite, quite important and quite, can be quite problematic. But I think it's just a few things that we need to bear in mind and, and be prepared, or to prevent them, and then, and then that, that, that should cover that section quite, quite nicely, and, and obviously we need to, we, we need to talk about the ultimate complication that it will be obviously the, the cardiopulmonary arrest and, and obviously how to, how to manage it. Some important factors that we need to, that, that we need to discuss about is, or at least to outline is, many of these complications tend to appear, based on the, the experience or the level of experience of the, of the person performing anaesthetic or the level of inexperience.
So sometimes it's the, not necessarily the overall experience, but it's actually the experience in that particular procedure. And, and with that type of patient, obviously, very often and over the years I've seen this as well is the lack of vigilance. Sometimes actually rushing things that you can see down there has, plays, plays a little bit of a, of a factor as well.
Inadequate, examination of the animal. Sometimes, actually, of course, taking the wrong decision or administering the right, the, the wrong, the wrong, the wrong drug, etc. Can make a difference, but, that doesn't seem to be the, the, the most common place in me, in my experience, .
A very, very, very, very often, emergency situations, emergency status are associated with complications. That, that was actually studied and that has been proven in, in, in human, in human anaesthesia, when, during emergency, during emergencies, especially out of hours, it's very common that complications occur. And if we are not vigilant, many of them can be life threatening and and that increases the mortality.
It was a very interesting study looking into, looking into that, a few years ago actually. Obviously, the lack of supervision and, and that applies to, to all settings. So if we don't provide enough supervision to, either the nurses performing the anaesthetic or our junior colleagues or ourselves, sometimes actually and actually obviously supervision to, monitoring our patients, that, that sometimes can lead into, into, complications and, and how to address and, and those complications, can, .
It will actually increase or decrease mortality based on the morbidity. And obviously, effective communication is fundamental, but sometimes when we, when we lack communication, sometimes these complications can occur, and I've seen that over the years now. So it's not uncommon that, .
The situations where there is no very effective communication then then leads to complications or very often small complications that they are not communicated effectively leads to a much greater problem and potentially the car pulmonary arrest and then, and then we, we've got a very serious problems that it could have been addressed a lot. In terms of cardiovascular complications, and so we moved to the first group of, of complications that we, that we are going to be doing . Talking today, we've got primarily hypertension, hypertension, and, and arrhythmias.
So hypertension is probably by far the most common complications that we tend to see. In, in the, in the hospital I'm working now at the moment, we probably see this in around 60% of our, of our animals at some point. And I'm talking about, and I'm talking about hypertension of m blood pressure less than 60 millimetres.
This is actually very, very, very common in the, in, in any setting. If you don't see that much hypertension in your practise today. Is it that because you're doing things much better than I am or or or because actually you are not monitoring the animals closely because the reality is that this is by far the most common complications that we tend to see.
The different causes, for, hypertension, the most common, so the most commons are, myocardial contractility. Hypovolemia, bisodilation, decreased venous return probably a little bit less common and severe bradycardia. To me, the most common, problems that we tend to see or the the most common causes that we tend to see is biodilation is #1 and probably bradycardia is #2, .
We use a lot of, metaomidine in the practise, in the practises I work at the moment. So, so obviously it's not uncommon that after the 1st, 20-30 minutes of, relative, relative muscle constriction that, that, metamidine can, can cause or text meotamidine is very similar, very often, . What happens afterwards is a little bit of hypertension associated with, with, with, with some degree of bradycardia.
So, . So in that case, I guess this is actually, rogenic, we, we, we sort of cause it in some, in, or, or, in some, in some ways, and biodation obviously we are going to cause it as well in many cases because most of the anaesthetic drugs are going to induce some degree of bioalation from the start is isofluorine, for example, or sevoflurane. Hyperbulimia, theoretically, in most of our patients, we are going to, we are going to have, especially if we have done a physical exam, the level of bulimia or the level of hydration is going to be fairly stable, but, and good, but we need to, we need to bear in mind that around 10% of the hydration is, is, is, is not detectable with, with just a, a normal physical exam.
Some of the consequences that we're going to hear, that what we're going to see or the main consequence is hyper perfusion, and that can lead, that can lead into shock. How are we going to treat hypertension, primarily, we are going to treat it based on, on whatever the, whatever the, the consequence is, or whatever the, the condition is, that it, that it caused the problem. So, so we are going to, We are going to, first of all, decrease the dose of pola anaesthetic that we are using.
That's going to help us a little bit with the, with the, some degree of the vasodilation that the volatile anaesthetic can use, but also with the decreasing con contractactivity. Both of those are actually dose dependent. So, so obviously trying to turn down the, the anaesthetic in the isoprehensive, that's going to be, that's going to be beneficial.
Of course, we are going to correct the bulimia. We are going to correct the, the blood volume that the animal has and, and, and we're going to try to hydrate the patient, if, if we didn't do it beforehand. And we're going to do that with, With, with fluids, either with crystalloids or potentially with a combination of crystalloids and colloids.
And it's important as well that we, that we improve the oxygenation. We know when the animals are hypoxic, and very often we've got a decreasing contraactility. The majority of the times, this is not really a problem because, we normally use 100% oxygen in many of our anaesthetics.
So that means that, that perhaps this step that I put there as a number 3, perhaps is not, is not really, essential in most of the cases because we are already gen the animal. when, when we have corrected the bulimia, when we have corrected the level of, of hydration of our patient, we have decreased the volatile anaesthetic, . What we can do is we can, we can try to, to increase the contractility and we can try to pass or constrict the animal a little bit.
And we are going to do that primarily with drugs and we will, and I will talk about them a little bit later on in a in a, in a, in a future slide. So, the first step, as I mentioned to you, I didn't put a picture here, but the first step is going to be, decrease the, decrease the volatile aesthetic as much as we can. OK?
After that, step two is going to be, decide to what that my patient needs, some fluids, beyond actually what I'm already administered. In the majority of the cases, and, I tend to, I tend to use some fluid, fluid policies. I tend not to overhydrate my animals too much, but I tend to at least, give them the benefit of the doubt and assume that I'm, and that, I missed that 10% dehydration in my physical exam.
If I find that in the, in the, pre, pre-anesthetic exam, the animal was more dehydrated and, and it was clinically dehydrated because it, it had, Very tacky mucous membranes, so we had the animal had skin din or something like that, then in that case, we will correct the bulimia, before, before the anaesthetic ideally. . In that case, what bots, what fluid bottles is I tend to use.
Normally, I tend to use, a 1010 millilitres per kilo bottles over 15 minutes or so, of crystalloids, or, or if I want to decide to use colloids, or for example, I tend to use normally crystalloids, I tend to give one bottles of crystallines first. And then, it's very rare for me to have to give, a second bottles of crystalloids or, or, subsequent. I normally, start, start the administration of collids straight away.
And normally I tend to use, around 3 to 5 millilitres per kilo of colloids with a gelatin, so starches, like, for example, poli then in over a period of 15 minutes as well. Here you go, we can give it, as you can see here, Boivin, is probably my top choice if I, if I can, if I can, and I've got available stats. If not, you can use gelatins like, the gelatins are a little bit, short, are a little bit shorter lasting.
So, so that's the reason why I tend not to use them very often. Normally, the half-life, is shorter. Normally a bolus tend to last probably no more than a couple of hours at the most.
. And volumen is much longer lasting and that's the reason why I tend to use it most. Yeah, after, I've used, I, I've used this, this fluids, and I, all this therapy and I, and I still have pressure. I start thinking about the use of, dopamine, for example, some catecholamines that you're going to have, probably in your practise, the, the most common one that people tend to have around in practise is probably dopamine.
Dopamine works, both, increasing contractility and increasing actually, after low increasing, partial constriction. So probably it's a quite versatilera. On the other hand, I tend to say that it's a little bit of a dirty rag.
It's a dirty drag because it doesn't seem to, it, it, it works on many receptors, and we don't know actually which one is the one that it was more beneficial for my animal and that's the reason why clinically I tend to use it less and less, but, but I understand that it is very beneficial and very versatile, and that's the reason why most people have it in practise. So the, the, the rates are going to be probably between 5 and 15, so 5 and 15 microns per kilo per minute. And normally we need to dilute it and we need to use a syringe driver to administer to our animals.
. You can actually use all the drugs that they have exclusively vasoconstrictive effects and, and that can, that phenylephrine, for example, is, is an example. Phenylephrine is an alpha one agonist, and so that means that only provides vasoconstriction. It's a, it's a drug that, for example, I would choose to use, in a, in an animal with, that is hydrated.
That is still, that is hypertensive, of course, that is hydrated, and, and it's a reasonably young drag young dog or or cat that basically has normal contractility or I suspect that the animal has normal contractility. It's a very potent drug. It needs to be diluted as well, and it needs to be given very slowly with with .
With the use of a syringe driver, the doses are are around between 1. Some people use 0.5 microns per kilo per minute, and the, and the range is between 0.5 to 4 microns per kilo per minute.
But then normally we start with the lowest end, with the lowest end of the range and we, we make our way up if, if, if needed. The What about hypertension? Does it, is it, is it something that we tend to see very, very often?
Well, in the reality is, is, is, as I, as I put here is very rare in animals. In, in people has, has been associated with, with an increasing morbidity and mortality perioeratically. So episodes of, of hypertension intro are not good either, at least in people.
In animals, we don't really know that much. The, the majority of the times it seems to be related to drugs, the administration of drugs that we, that, that, that either because we have overdosed catecholamines or or the animal was, was no more intensive and perhaps we gave atropine by mistake or something like that and then, and then they become hypertensive. Sometimes it can happen with pain as well, and, and it, and, and it can happen as well with, with cardiac conditions like for example, heart failure, fluid overload.
It could happen as well in, in the case of of herniation of the brain stem, in a, in a patient with a, with a cranial tumour or something like that as part of the cushion tree. But the reality is that, as I said, it's not really that common. And the majority of the times is, it lasts a few minutes and unless it's something sinister unless it's, it's cardiac pathology or neurological pathology or something like that, in that case, it needs to be treated and and we can actually treat it with a with .
Bissodilators, like, for example, nitroprusate or ACE inhibitors or something like that. And under anaesthesia, as I said, is very rare. Normally, the, the most common ones that we tend to see are either drug-related and they are self-limated.
So normally, as the drug wears off, the, the effects wear off as well and . And it, or it can be related to pain and in that case, as soon as we treat the pain, and remember that under anaesthesia, I will refer in this talk about pain, but the reality is that there is no emotion involved, so, so, we should probably call it, call it more appropriately, no deception, but, just because, just to, to, to relate and talk about something that everyone can relate to, I I I'll continue using it. Hypertension is, is probably important as I put it here at the, at the bottom of the, of the slide.
It's probably more important when it's, when it's, chronic in the presentation, when it, when it's presented over a long period of time, because that can have actually some, some hearty fat and kidney effects and probably as well, it can, it can induce some, some degree of rectin attachment, etc. Etc. So it's, it's a few things that Perhaps, hypertension is very important in a, in a clinical presentation, but perhaps under anesthesis, is in general not that common.
When we are facing the anaesthetic of a patient that is hypertensive chronically and is on treatment, we need to be careful because the majority of the time these animals are slightly dehydrated. And very often are, obviously on treatment, for example, ACE inhibitors or something like that. My recommendation is, is that those drugs are stopped 24 to 48 hours before the anaesthetic and And we prepare ourselves, for, for actually hypotension, the majority of the, during the anaesthetic, the majority of the times these animals are actually, incapable to maintain their blood pressure by themselves.
So as soon as we biodilate them, very often actually they, they tend to have Very severe hypertension in jobs. So, so we need to be prepared to to treat that, to monitor that, of course, very carefully and, and as soon as it is present, it presents the hypertension treated, treated very, very rapidly because some of the, some of the worst hypertensions I've seen, clinically were in patients with . With with treatment for hypertension.
What about arrhythmias? Well, arrhythmias are, in general again, probably not super, super common, under anaesthesia. They, they occur sometimes.
They can be very common depending on the procedure that we are doing. So obviously if we're doing cardiac, cardiac procedures are extremely common or arthrochotomy or something like that, just basically for interacting directly with the heart. But the, but the majority of the times and if we are not doing that type of procedures, I guess the most common problems that we tend to see are in the case of hypoxia, or in the case of electrolytes or pH imbalances or acid base balance.
Sometimes, hyperlactatemmias, poor perfusion, shock, etc. Can, can actually lead into arrhythmias as well. One of the most common, conditions that you are going to see in practise that it can lead into arrhythmias is, splenectomies, for example, hemangiosarcomas, in the spleen, or, for example, DVDs are, sometimes, induce some degree of, Of arrhythmia, the majority of the times due to the hypertension, the shock, and the hypoxia, and the myocardial hypoxia.
I guess the, the, the, the majority of the times what we need to do is to assess the type of arrhythmia that we are facing. We are going to, we are going to have a look about the, the, the, hemodynamic effects, the frequency of that, of that, arrhythmia, and what consequence this is having. .
So in Based on all that, we will decide if we need to treat the arrhythmia or not. I'm just going to, this actually happened to me, last, two days ago, on a Saturday. This patient was This patient was stuffing that it came for, for a pyometra.
And you can see I'm just going to play it again just from the beginning, at, at here is in sinos rhythm reasonably, reasonably slow sinos rhythm and suddenly has flipped into an escape rhythm. with a very similar actually, I can, although here appears to be, it's lower the, the rate, actually, the rate was fairly similar, was around 50, in both cases. The blood pressure, were actually at this point, it was OKish, a little bit low perhaps, still with it, it's still above 60 or just on, on the dot with the mean of 60, .
I treated the, the, this, this arrhythmia with an anticholinergic, so I gave, this dog, two doses of atropine. And neither of them actually, made any improvement and, . And basically, after, after that, I thought about the different options that, that we had in, or I had in my hands, but at the end, I decided not to do anything, because the pressures were actually, they improved a little bit, beyond that, and, and basically the rate was slow but not, nothing to be that concerning.
So I decided not to, I decided not to do, To do anything and I, I just basically didn't really treat the, the, the arrhythmia. . So, I guess depending on the type of the type of arrhythmia that we are going to face, we, we, we, we need to decide what treatment we are going to use.
So we can divide the arrhythmias in in bra arrhythmias, that that's something that we tend to see fairly often under anaesthesia. So it does sinus, bradycardia, AV blocks, in the first or second degree AV blocks. And, and very often we are going to try to treat that with, with atropine.
You can also use glycoperolate. Some people prefer one, prefers one over the others. I'm not that bother.
I use, I normally use atropine because it's more readily available for me. Glycoyolate is a little bit longer lasting. Other than that, both are anticholinergic, so both it will speed up the, the heart rate of the, and the heart rate of the animal.
So brother dysrhythmias are probably are probably one of the most common arrhythmias, and they are easily treatable for, for us. So if you've got an animal that has got an a block, it's got a, or, or is, or an animal that has . Sinus sinus bradycardia and, and that's affecting the blood pressure and the blood pressure is low, then speed up the heart rate with, with one of these drugs and normally the problem disappears.
What about the one, what about Tay this right? Oh, actually, first of all, what about a 3rd degree AV block? 3rd degree AV blocks are, are that AV blocks that normally you see P waves on their own, and with, and with no association, you see an escape rhythm from the ventricle.
OK. The reality is that there is no, there's the only treatment for that pathology is, is actually, . a pacemaker.
You can actually use atropine or, or glyco. Sometimes, some of them can be actually, atropine responsive, but most of them are not. So, so the only option is to use a pacemaker.
So the question is, If the escape rhythm is fast enough to maintain blood pressure, probably what I would do is to finish what we are doing and refer it to a cardiologist, for a, for a pacemaker placement, implantation if, if the animal, if the client is happy and, and, and they, they can afford it. But the reality is that, . It's not something that we can actually fix in, in, in, in practise routine.
What about if with the, with the, tachy dysrhythmias when we see actually, sinus tachycardia, very simple to treat. We normally treat it with, with, normally what we'll do is, is normally associated with, with, pain. Or with, and, or with actually, stress or something like that or awareness, and very often what we do is just deepen the aesthetic, even a painkiller, normally we solve, we, we, we sort out the problem.
If we see, ventricular arrhythmias, then, which is probably the most common arrhythmia that you're going to see in practise by BTC, or, or BAC ventricular tachycardia, the, the treatment of choice and super readily available is like. So I normally give in a bottles of of 22 milligrammes per kilo lidocaine or linocaine. It's the same, it's the same thing, it's the same drug, two names for the same drug.
. So, you give 22 milligrammes per kilo of lidocaine ID and both in cats and dogs actually. And, and then I see the, I see the response. If there is a positive response, but there is no enough duration of the action, sometimes what we do is to put it on a, on a, on an infusion.
You can check in the formulary, the, the infusion, the infusion rates. Luckily, actually for us, the, the antiarrhythmic doses of lidocaine and, and the analgesic doses of lidocaine are actually almost equivalent. So, so, very often those BPCs can be triggered by, by pain, but, by giving lidocaine actually we are, we are hitting two birds with the same stone because we treat also the, the, the, the pain.
And another drug that I've, I tend to use occasionally and probably is the only, the only other an rhythmic drug that I've got available in anaesthesia, at the moment is a neutron. So very often when we've got, a supventricular arrhythmia or when, or when it's not responsive to lidocaine, sometimes we, we, I use a mutterone as As, as the other drug that, that, that I tend to, I tend to use, it's not something that I use very often, but it, but it, we've got it available, just in case, then. When are we going to treat a BBCs?
in general, we tend to say that BPCs are going to, ventricular premature complexes. We are going to treat them, when they are multifocal. So basically, the appearance in the ACG change between different, between different complexities, when they are very frequent, and normally we tend to say that when they are more than 1015 a minute, probably we should, we should treat them, and, or when they are impacting the, the hemodynamic of the, the hemodynamics of the patients.
So when they, when they are impacting the perfusion or when they are impacting the blood pressure is when we tend to, when we tend to, treat them. Well, ventricular tachycardia will, will normally treat it always and sometimes we've got . Another, another arrhythmia called, accelerated the ventricular rhythm, which appears to be very similar to ventricular tachycardia but a lower rate.
And, normally when it's, it's lower than 120, 1 120, 130 bit beats per minute, per minute, and, and very often those, that rhythm, doesn't really compared with lidocaine into so rhythm. But, I normally try it regardless, but if I don't succeed, I don't continue, I don't continue giving more light. What about respiratory complications?
Just moving on on that. Respiratory complications, the most common that we are going to see are, probably the most common actually under anaesthesia attasis, to be honest, and hypoventilation. The, the, in, in itself, those two are, something that we see probably every single day.
And probably are minor complications. So, so probably we don't really pay a lot of attention to them, although they, they exist. All the complications that probably are a little bit more severe are, are the, the first rate are we abstraction, aspiration, and bronchospasm.
So, our way of abstraction, it can be from laryngeLS spasm, for example. This is a dog, but you can see it in a cat. Actually, this is, you can see the, the the Everti saccules there, very common in Mercephalics, .
And probably brachycephalics are, are all the time obstructed and they've got obstruction and, and we anaesthetize them in many cases actually to correct that obstruction. This one actually has a normal, normal so . In some, in some cases, it has to actually lead into into manage it, place a tra trache, a tracheostomy tube and temporarily or like in this case permanently.
This dog had a laryngeal tumour, and, and it needed a permanent tracheostomy. And obviously, as the number one, the number one case that we tend to deal nowadays with our obstructions is, especially upper respiratory obstruction is brachycephalic and yeah, and, and the reality is as soon as we intubate the patient or we put on a track tube or we bypass the problem, then the complication is, is, is sorted. In this case, this, this cat has actually had a, a foreign body in, in one of the, at the level of the carina, has a stone at the level of the Carina.
The important part to, to see in this video is you can see the thorax when the animal is breathing in, the thorax goes in. We, we, we said that we normally call that paradoxical breathing, super common of, of respiratory respiratory obstruction. Obviously, in this case, it's not something that by intubation is going to get bypassed, it is something that, that we have to sort out first and we did, we did, we removed it with fluoroscopy.
So it's something that, that it can be, that, that it can happen. Trachea, tracheal collapse is something that again, it can, it can give you that paradoxical ri very, it behaves very similar to, to, it behaves very, very similar to, to upper obstruction. The advantage of tracheal collapse is that the majority of the times on the anaesthesia, as soon as the animal is deep enough, this doesn't seem to be a problem.
It, it normally doesn't really give us clinical signs. And if it happens by ventilating the patient, by inducing, inducing positive pressure ventilation, we normally can overcome the problem of ventilate the patient. So, obviously the solution, the permanent solution, it will be to put on a stand like in this case.
But even if you are facing an, an animal like Like a George terrier or something like that with tracheal, with, with tracheal collapse, what you can do is, have the animal, sufficiently anaesthetized probably will sort of most of the problems, but if they are very light and they, they start, breathing and obcting and give you that appearance of paradoxical breathing, what you can do is actually give some positive pressure ventilation just by, just by manual ventilation and, and then the problem normally sorted. What about bronchospasm is bronchospasm is a little bit, the majority of the times that we tend to, when we tend to see bronchospasm tends to be drug-related. So because we have given antibiotics or the animal develop anaphylaxis or degranulation of the muscles or something like that.
Normally I tend to treat them with, I tend to treat them with increasing the, the, oxygenation of the, of the mixture of that we are using. If you're using 100% oxygen, you can't really do anything further than that. The other thing that we can do is to give bronchodilators, like, for example, tebutyin.
And, and we can give actually IPPV . So those, those three are probably the three steps that we tend to do when we see bronchoconstriction. The, the majority of the times actually, a bronchodilator like trabutylin or salbutamol works really, really well and very rapidly.
Alectasis, are, are probably some of the most common things that we tend, some of the most common problems that we tend to see, and 90% of the times, or 90% of the people don't pay much attention to them. So, very rapidly animals in, that they are under anaesthesia, especially if they are in dorsal recumbency, they form metalletais. So you can see here, that's using 100% oxygen, and basically, after a period of time.
And, and they format like this, very rapidly. This, this dog was necessary with only 40% oxygen, and we know that when the, when we use high concentrations of, of high concentrations of oxygen, they, we tend to have more aletais for it. .
Ideally, we should probably use lower FIO2s, but I understand that in practise that sometimes it's not possible. So at least we need to be aware of that and we need to monitor it. And how are we going to monitor this?
Of course, I'm not talking about doing a CT, every time that we do an anaesthetic, but the important thing that we need to do is to monitor pulse oxymmetry in recovery, because these animals all this long. Is not, is not open, so it's not having any gas exchange. So that means that, that we are losing more and more and more lung capacity over time.
When we use 100% oxygen, that's not visible because we are given so much oxygen that we need pretty much and, very, very small part of the lung to oxygenate the haemoglobin. But the problem is, as soon as we move that animal from 100% oxygen to room air, 21% oxygen, then, then problems can occur. So, that's the moment when pulse oximetry is essential and we need to monitor, we need to monitor haemoglobin saturation.
And as the animals are recovering because it's when anything can, when, when we can actually reveal problems that we didn't see before, because we were given a masking ourselves, and masking the patient by giving 100% oxygen. So, so please, from now on, just maintain the pulse oximeter during the, during the recovery, at least in the, in the first, in the first several minutes. .
To make sure that the patient is saturating is saturating reasonably well, and then, and then we can all, all relax. How, how long? Probably 55, 10 minutes at the very least.
This satellitetasis, traditionally, we used to, we used to think that the satellitetasis disappeared very rapidly. But the reality now is that now we know that this sateletasis can take days to sometimes weeks to disappear. And And also my impression is that this, this, this, can contribute to, to morbidity and, and can contribute to, to, it plays a role in some of these animals that all of us, we have had That they come back after the, further recheck after the surgery, and the, and the client is telling us that he had a little bit of honking cough and you have a little bit, and it was a little bit of colour and it, and, and, and I'm wondering if these satellite this are actually giving us a little bit of focal pneumonia, the animals don't, just basically cough for a little bit.
We assume that this tracheitis, and we just basically, think, well, it was the AT tube, of course, we, we need to blame anaesthesia, but we'll just say it was the AT tube and, and that's sorted. But I'm wondering if it was something, something else and it was something a little bit, a little bit, . Perhaps worse than, than just a little bit of tracheitis.
And it's, and it's something that it can unfold on something a little bit harder to treat or, or worse for the animal. Having said that, how often do we see, pneumonia post anaesthesia in animals? Probably not that common.
So, so perhaps, it's me just overreacting and it's not, it's not perhaps the, the, the frequency is not that common. . What are the clinical signs of that, as I was saying.
So, in the worst sex scenarios, we are going to be cyanosis, but the majority of the times we are going to see hypoxemia, hypercapnia, and, cyanosis and thisnia. It's probably in the worst sex scenarios, to be honest. The majority of the times, hypoxia is also a relative hypoxia hypoxemia.
So if the, if the lung was fully open, perhaps we'll have a a partial pressure of oxygen, arterial partial pressure of oxygen of maybe 500 in maybe my animal is 100 millimetres microbe, but that's, that's sufficient to, to maintain a normal SPO2. So, so perhaps I'm not going to, I'm not, I'm not seeing that. But obviously hypercadnia is something that we, that again, we can pick up sometimes.
So, That's things to, that's something to bear in mind. This is obviously if hypoxemia, is maintained over a period of time, we will have obviously lactic acidosis, but it's something that we can, that we can see, clinically in some of our patients when, when this, when this case is, become very, very severe. Only when it chronifies, we'll see, either a cerebral edoema, dipsia or polycyemia.
The majority of the times, The, in the event of hypo hypoxemia, the pulmonary vasoconization should kick in, but anaesthesia blunt that, that actually comp compensatory mechanism. So we tend not to see it. OK.
And this is what, what, what I, what we were, what we were talking about. So this is the oxygen dissociation curve. The majority of the times under anaesthesia, we are in a hyperoxemia, status.
So basically, we are, we are actually here on the right, in the far right, actually, the, the, the PAO, the PAO2. It probably will be in the 500s, so really, really far on the right side. So, and that's the reason why we cannot really see much.
So what we need to do is to force the animal, and, to be in a more Normal, inspiratory fraction of oxygen to be able to reveal that, to rebuild this curve. And the only, and the easiest way to do that is, is during the recovery and I think it's fundamental, it's fundamental that we get into the habit of monitoring, of monitoring that. What about hypercapnia?
Hypercapnia is fairly, is something that we tend to see fairly common and and and anaesthesia, because we tend to induce with all the drugs that we, that, that we give, we, we tend, we tend to induce hypoventilation. So that's the reason why we tend to, and that's the reason why we tend to see that and that can have an effect of, of myocardial contractility, etc. So, So what about the other complication that miscellaneous that I was talking about that sometimes we, that, that sometimes we go.
Well, the most common one that we are going to see is hypothermia. Hypothermia is by far, the second most common, well, actually probably is the most common complication, perhaps not so much in the UK. But, in, in, in countries with reasonably hot climate is, is very, very common.
Here in Australia, we probably have around 70 to 80% of our animals have some degree of hypothermia between mild to moderate hypothermia, by the time that we finish the, the, the procedures and that's because of we've got the aircon on all the time. Also, if you are dealing with, animals of a small size, again, that's going to increase the, that, that, that's going to increase the, the likelihood of having hypothermia. So overall, it's probably the number one complication that we tend to see under anaesthesia, and, the #2, as I mentioned before, is hypertension.
I'm going to mention a little bit postoperative blindness. This is only applicable or primarily it's important in cats. And then, we'll talk about bad recoveries in general, either because they are very slow, because they are very excitable, and we'll talk about anaphylaxis, I guess.
So hypothermia, super common. The majority of the, of the, the majority of the reasons for it is, is just because anaesthesia actually affects the thermoregulation, the, the thermoregulation centre, and that means that the animals actually start losing temperature and they're not capable to maintain, to maintain temperature. At the same time, or maintain heat.
At the same time, we, we, we bioate the animals, so obviously we increase the losses. Very often we, we, we can increase the losses also when we've got open cavities, and obviously we lose heat, through evaporation, through the respiratory system as well. .
Just because we bypassed the nose, that obviously that is a heat, is a heat exchanger. And, and sometimes we lose temperature just by contact, just having the animals in contact with cold surfaces like the table, etc. Etc.
It's, prevention, what, what's best, preventing the problem or, or, or, or reverting the problem. Well, of course, it's not, it's not, it's not very difficult to understand that prevention is, is, is the way forward, but at the same time, it's very difficult. That doesn't mean that we have to ignore it and we have to just let it happen.
But I think, when it's lost, the heat is very difficult to, to, for, it's very difficult for us to actually Add it or give it to the, to the patients. So, What are the consequences that we can have? Well, the consequences primarily are going to, are going to be the slow recoveries.
It's going, it can have directly defect, to, to the heart and it can decrease con contractility and induce, and induce arrhythmias. Also, when it's very, very severe, can cause biodilation as well. So initially hypothermia induce some degree of vasoconstriction, but to maintain the temperature in the core.
In the, the body temperature, but the, the, the problem is when it gets, when it, when it gets, past a certain threshold, lower threshold, very often, the, the, the, the body realises that sort of there's not much point to, to vasoconstrict because it's not going to save any, any heat, and then, or we cannot maintain it any further and basically baolates from there. . It increases oxye consumption primarily by shivering.
So, shivering, I'm sure all of us, we have experienced on, at some point and it's, it's, first of all, it's unpleasant. It's not painful, but it's unpleasant. And as, and on top of that actually increases oxygen consumption.
So, so very often, we need to try to promote, The, to promote actually hip prevention, to make sure that the patients, that the patients are not shivering that much. . And I think probably, I'm almost certain that we always have seen, or we have seen at least at some point in our careers, one animal that it was very, very, that it was very cold, 32, 33 degrees, and basically they are not shivering.
It's not abnormal. It's, it's actually fairly, fairly common, thing to happen when the temperature is very low, the body doesn't, doesn't, shiver. And that's because, the body is trying to always maintain the lowest, the lowest energy consumption possible.
So when there is no point. To actually increase muscle activity to, by shivering to maintain temperature, it's not, it, it basically the patient, the, the, the, the body decides not to shiver. So, you'll notice that if the animals are shivering is because they are very, are, are normally close to 37 degrees, normally 35, 36, in, in those lines, and then they shiver.
In those cases, actually oxygen supplementation it can be actually quite helpful, especially if the, if the animals may have a respiratory complications or, or, or respiratory issues, etc. Something to bear in mind as well is, is the, the hypothermia decreases the immune system and, and it decreases he the healing. So it's something to, to, to, to take in consideration.
In terms of prevention, you can actually, use something like this device is a, this is called a HME or heat and moisture exchanger. Basically what it does is substitutes a little bit of the nose. So by, by, by putting on into the tube, we are actually bypassing the nose and the, and the nose maintains the moisture, maintains the heat, and, and exchange it.
This device artificially does that. Basically, it's a, it's, a device that is, is just basically full of, wrapped around cardboard pretty much and creating a very poor surface that it it prevents actually the moisture to go into the breathing system. Obviously, you can use heating devices and wrapping around the animal that's going to prevent radiation, and convection, etc.
So, so the, the, the prevention is very, very good. You can use, Air Force, blankets like the Berhaer style. You can actually use something like the shock blankets or space blankets that can be quite helpful as well, and we use them routinely here, and that's, and that's trying to prevent the, the radiation, losses.
What about the cortical blindness? The cortex blindness is primarily something that cats tend to suffer more than dogs. It's just basically, due to, a very unique, cerebral, perfusion, in the, in, in cats.
And, and basically, the, the cortical, the cortical hyper perfusion and the cortical hypoxia cause a cortical blindness. And the, and the way is, the only way to, to, to avoid this is by prevention. We We found that actually in a very, very interesting study that it came from Cornell, they found that when we use a spring loaded, when we use a spring loaded, a mouth gags during, during dentistry or for example, endoscopy.
We can, we can have, as you can see here, we can actually, block and occlude the, the perfusion of the brain that it comes and the, and, that it comes from the the maxillary artery. So, so, So that's the, that's something that we need to bear in mind and, and basically don't use those devices in, in CADs. This study also found that when you use a needle cup that is 22 millimetres or, or more, it's again as bad as using a spring loaded mouth gag.
So these, these devices have to be actually erased from our practise and especially when our feeling and patients are around. . What about difficult recoveries?
Difficult recoveries are the majority of the times, are going to be related to, in my opinion, well, we can classify them in, into either slow recoveries or basically excitable recoveries. Slow recoveries are the majority of the times due to a slightly overdose of drugs. So, So sometimes people tend to give, administer painkillers, especially potent opioids, just before extubation.
And then that means that the animals get really deep very rapidly and just before, just before the extubation and that obviously, takes a little bit of time for them to eliminate it and to, to be able to, and to be able to come out of that. . Sometimes, it can be related to all the things like, for example, hypoglycemia.
So it's worth actually in those cases, oh shock, so it's worth, it's, it's worth in this case is monitor blood pressure, monitor heart rate, monitor blood blood glucose, at least we, to rule out the most common problems. If we've got an animal that is hyper excitable and during recovery, the, the easiest option that, or the, the, the The, the ways to, to go for is trying to troubleshoot was the main, the main reason why it's doing that. It could be a lack of a lack of sedation or a lack of premed, and that, that means that we can re-sedate the animal if needed.
It could be discomfort, it could be basically that the patient needs analgesia. Sometimes I've seen it also with animals that they, that they have full bladders, etc. So obviously, preventing that by emptying the bladder before before recovery can be quite helpful.
And in general, I tend to extubate a little bit early all my patients. So I tend to extubate all my, my, my animals, dogs and cats, pretty much when they've got a strong blink and they are starting to, to, and, they, they've got, and a strong part people reflect on the eye, and the eye is starting to become a little bit more central. And the majority of the times I, as I'm extubating, then, they swallow.
The exception to that, of course, is brachycephalic dogs. So, Or if the animal has shown regurpitation during the anaesthetic. In those cases, we will, we will extubate late, but knowing that they can have a little bit of, they can have a little bit of rocky recoveries because extubation is quite stimulating in general.
And just in the last few minutes of, of this, of this presentation, we are going to be, we, we will talk about probably the ultimate complications that sometimes occur. So, the, the, what happened when we've got an animal that, that, that is, is suffers a cardiopulmonary, cardio pulmonary arrest under anaesthesia. So, we will, if that happens, I guess the first, the first step is, Is, number one, stop the, stop the, the administration of any drug that we are giving to the animal at that point.
So that means, no, no polateral anaesthetics. We will turn off the isoflurane or the sevoflurane. We will stop nitrous oxide if we are, if we are using that, we'll just give 100% oxygen.
We, . And There's no, there's no reason for actually increasing the fluid therapy unless the animal is not on fluids. So, so in, in my opinion, I don't really think that we need to actually start using fluids as a, at a shock rate.
I, I think we need to make sure that the aim that the animal has, of course, a patent, a patent IV and, and we are administering fluids at . At the rate that you are normally using at that point, so 5 mL per kilo, 10 mL per kilo, 4 mL per kg, something in those lines. Obviously, under anaesthesia, we're going to have secure already on our way, or we, I presume we should.
And, and the animal may, may or may not be breathing. If it's not breathing, we will start ventilating through the breathing, through the breathing system that we are using at the time. And the res the respiratory rate that we are going to use of the of the ventilation rate is approximately 2020 to 30 breaths per minute.
Ideally, if the animal is not intubated at the time and at rest just at the, at induction, we will check them out, make sure that there's no any content there, and we will intubate. The minimum monitoring that, that, and that we need during a cardiopulmonary resuscitation is an ECG and capnography. We know now that probably the Doppler, is, is not that accurate because very often with the movement of the compressions, we might have, we might have actually a false as a false positive.
Capnography is a good, is a good way of assessing our, our, compressions, compressions, because if we are being effective, we should have some degree of, of circulation and some degree of CO2. Normally, we tend to say that something around 10 millimetres of mercury of entitle is adequate. And very often is, is, that would be optimal, to be honest.
We could say that probably around 6 or 7 is sufficient. . Cardiopulmonary resuscitation cycles, so, is, is basically the manoeuvres for a period of 2 minutes and we considered that, we need to complete a cycle before actually changing people and we need to complete a cycle before actually assessing the patient and change, and change the therapy.
So, at the very least, we are, we are going to give 1010 breaths per minute. My advice is probably I give around 20, and don't stop them, in relation with the cardiac compressions. So ideally we, we will have two people at the very least or more and and the breaths are going at their own pace and the, and the, the the cardiac compressions are going at their own pace.
If we only, if we only have one person performing the whole thing, normally what we tend to do is, is, is tend, we tend to do two breaths consecutively, and then 30 compressions after that, and then again, 2 breaths, 30 compressions, and so, and so on. But in general, the success is, it tends to be a little bit worse. In terms of the cardiac compressions, we tend to do any around 100 compressions or the range, it talks, then, then generally, the, the recovery that, the recover initiative, talk about 100 to 120 compressions per minute, and the compression has to be to be effective, it needs to compress at least a third or half of the, of the width of the chest.
So, the A few years ago, there was a, there was a news in the, in the media that basically people training with, with this song, stay in our lives, from the beaches was was associated with was associated with a good outcome because it, it, it brings some metro basically mental metrics into that they're giving the right, the, the right bits per minute, because this song actually has 103 bits per minute. There's a few studies that has been shown that, that, that it can be positive, especially, for, for some person, from some type of personnel, like in this study, they found that, That it was positive in, in teaching, and teaching them how to perform cardiopulmonary resuscitation. They, there are also some reports that it shows that especially for lay, lay people, it might not be even more, it might not be that efficient.
They have also tried all the dra all the, all the songs like for example, this one, they, they used, you can see down there, they use the Macarena from the, from, by Los del Rio, and, for some reason, actually, they decided to, to, train school children to, to how to, to resuscitate, people of, of course, they use a manicure for this study and they found that again, it can be, it can be quite helpful. And, and for some reason, actually, and I don't know if this is, if this is correct or not, but again, it has 103 bits per minute, which it seems to be Very, very, very accurate and very, very similar to staying alive as well. So, maybe that's the type of song that we need to, that we need to find.
In terms of how to perform the The, the compressions in, in very large dogs, we will use the highest point of the chest wall. Don't, don't go over the, over the heart, we just go on the highest point of the, of the, of the chest and we'll compress between 5 and 1/3 of the width. .
When they are a little bit, a, a little bit thinner, a little bit smaller, when they are not, not that deep-chested, we can go on top of the heart. And when they are actually, really round-chested, like, where, like, for example, brackacephalic, sometimes different species like for example, in pigs, we tend to do this as well. So, so the best option is to put them on their back and do the compressions of the, of, of the thorax, from, from above the sternum.
In, in cats are very, very small dogs, what we can do is just put basically our four fingers in one side of the, in one side of the chest wall, the thumb on the other one, and basically, perform the compression just with our hand rather than, rather than actually with the with the arms as we will do in the other, in the other, in the other two in the other cases. In terms of advanced support, when we talk about drugs, I think what we need to concentrate in the, is obviously, do we need to give any, any reversal? Do we need to reverse the drugs, either, alpha 2s or opioids, etc.
And in that case, that's something that we need to do, we can do straight away or as soon as we can. And, and probably the, the drugs that there has been associated with the best, with the best results, of course, is adrenaline and plus minus atropine. So adrenaline, this, the, the recover initiative talks about +22 doses, the low dose, so 0.01 milligramme per kilo, and high dose 0.1 milligrammes per kilo.
And, and normally you start with the low dose and then, and then if it doesn't seem to be affected, you go to the high dose. And Atropine, atropine, we tend to use it only when if the animal comes back with a really reasonably low rate. Sometimes we give atropine, sometimes we give atropine As, I guess as, as this aspiration sometimes, you can, very often during CPR and very often people alternates adrenaline and atropine.
The reality is adrenaline should be sufficient, but in desperation, we, we, we try to use something else and we try to add atropine there, but the reality is very often if it does, if it's not helping, adrenaline is not helping the majority of the times, it's, it's just probably the outcome is not going to be very good. We tend to use lidocaine if, if, if only in the case of having, the animal or coming back with a, with a ventricular arrhythmia. Of course, the fibrillation is something that, that we might use if the animal comes back with, either a fibrillators or it comes back with fibrillation.
The most common arrest in, in a small animal. Tend to be actually assistedly. So, so a journalist seems to fix those ones, but also we need to bear in mind that especially under anaesthesia, the animals are receiving already a high FIO2.
They are already monitored very closely. So, so, in the majority of the cases, actually there's a very good reason why they are arresting. So it's not that common that, that actually, The animals, they might come back, but very often they rearrest, etc.
So the outcome in general is not as good as it will be in hospitalisation. Here, you can see the, the, the CPR algorithm. I think this should be actually displayed in every single practise and in every single theatre just to, to, to make sure that, that, that it's always in our hand, in, in our heads.
That's, that was developed by, by the recovery initiative and, and I think it's, it's fairly, it's fairly self-expectatory and very helpful. And, and again, this was, was actually developed as well, during the, during the, recovery initiative or by the recovery initiative. And again, it's a very, it's an easy charge to use, we tend to, we printed and laminate it in our in our, a crash trolley, but you can actually have it laminated if you've got actually in the theatre or something like that.
That's something that you can, that you can have available. And that was everything that I wanted to talk, talk to you about. So, so I hope you find it useful and And, and, please start implementing some of some of the prevention techniques that we discussed here in in tomorrow if possible.
All right, bye.